Observation wheels such as the London Eye and subsequent wheels, such as the Singapore Flyer and the Star of Nanchang, contain two giant rolling element bearings in the center hub of the wheel. These giant bearings require a giant seal to encompass the bearing in order to hold in lubricant. When utilizing giant bearings in an observation wheel, the fact that components can only be produced to a certain size becomes a constraint on the overall size of the attraction. The engineering considerations that are present in the design of such large systems are materially different than those that exist with respect to smaller systems.